1. Field of the Invention
The present invention relates to a mobile ballast cleaning machine for continuously receiving ballast from a ballast bed supported on a subgrade and supporting a track having two rails, and for cleaning the received ballast, which comprises a machine frame extending in a longitudinal direction along the track, undercarriages supporting the machine frame for mobility on the track in an operating direction, an excavating chain mounted on the machine frame and arranged to excavate the ballast to expose the subgrade, a ballast screening installation arranged to receive the excavated ballast from the excavating chain and to clean the received ballast, a ballast conveyor unit extending in the longitudinal direction and having an input end receiving the cleaned ballast from the ballast screening installation and a discharge end, a chute arranged at the excavating chain for receiving the cleaned ballast from the discharge end of the ballast conveyor unit, the chute having at least one outlet opening, and a power-actuated, vertically and transversely adjustable track lifting device mounted on the machine frame.
2. Description of the Prior Art
Such ballast cleaning machines are very well known, as exemplified by Swiss patent No. 651,869, published Oct. 15, 1985. In this ballast cleaning machine, the cleaned ballast is conveyed to a ballast distributing device arranged in the range of the ballast excavating chain, two ballast discharge chutes positioned one behind the other in the longitudinal direction of the machine being associated with the ballast distributing device. The ballast distributing device is equipped with a controllable distributing baffle enabling a predetermined amount of cleaned ballast to be deflected to the rear or the front chute, depending on the depth of excavation and the desired depth of the redistributed cleaned ballast layer. The cleaned ballast deflected into the front chute is discharged directly behind the excavating chain on the exposed subgrade and is planed and compacted with an adjacent ballast compacting device. The cleaned ballast portion deflected into the rear chute is discharged therefrom onto a ballast distributing conveyor band extending in the longitudinal direction and conveying this portion of the cleaned ballast to a point immediately in front of the rearmost undercarriage of the machine where it is thrown into the cribs. This arrangement has the disadvantage that the amount of cleaned ballast to be distributed cannot be accurately metered.
U.S. Pat. No. 3,685,589, dated Aug. 22, 1972, discloses a ballast cleaning machine in which the cleaned ballast distributing device comprises a storage bin for the cleaned ballast arranged immediately behind the excavating chain for discharging controlled amounts of cleaned ballast on the exposed subgrade behind the excavating chain, a chute arranged immediately in front of the rear undercarriage of the machine for discharging controlled amounts of cleaned ballast into the cribs, and two cleaned ballast conveyors extending in the longitudinal direction of the machine above the track rails and being transversely pivotal about respective vertical axes for controllably conveying cleaned ballast to the rear chute or the front storage bin.
British patent No. 2,097,846, published Apr. 3, 1985, discloses a ballast cleaning machine in which the cleaned ballast is conveyed for discharge on the exposed subgrade behind the excavating chain by a conveyor unit extending in the longitudinal direction of the machine between the screening installation and the excavating chain.